1. Field of the Invention
The present invention relates to a ceramic electronic component and a method for manufacturing the same. In particular, the present invention relates to a ceramic electronic component, such as a laminated ceramic capacitor, in which a terminal electrode is formed at the end surface of a ceramic component body and a method for manufacturing the same.
2. Description of the Related Art
FIG. 9 is a diagram illustrating an example of a conventional ceramic electronic component. A ceramic electronic component 1 contains a ceramic electronic component body 2. The ceramic electronic component body 2 contains layers of internal electrodes 3 and ceramic layers 4. The internal electrodes 3 are led to two end surfaces of the ceramic electronic component body 2. A metal layer 5 is formed in such a manner as to be connected to the internal electrodes 3. The metal layer 5 is formed by printing a conductive paste containing metal powder to the end surface of the ceramic electronic component body 2. The metal layer 5 is formed in such a manner as to wrap around from the end surface of the ceramic component body 2 to a part of the side surface. On the metal layer 5, a conductive resin layer 6 is further formed. The conductive resin layer 6 is formed by supplying a mixture of metal powder and a thermosetting resin, such as an epoxy resin, to the metal layer 5, and heat curing the same. The conductive resin layer 6 is formed in such a manner as to entirely cover the metal layer 5. On the conductive resin layer 6, a plating film 7 containing a lower film containing Ni or the like and a surface film containing Sn or the like is formed.
In the ceramic electronic component having the metal layer formed at the end surface of the ceramic electronic component body, a large stress is applied to the metal layer due to a thermal shock cycle in which increases and decreases in temperatures are repeated, sometimes resulting in development of cracks in the ceramic component body. Since such a stress is concentrated on the end of the metal layer at the side surface of the ceramic component body, cracks are likely to develop at the portion in the ceramic component body. When the ceramic electronic component is attached to a wiring board, such a stress increases due to the thermal shock cycle by the difference in the coefficient of thermal expansion between the ceramic electronic component and the wiring board. Thus, cracks are likely to develop in the ceramic component body.
It is described that, in order to avoid the above problems, the development of cracks in the ceramic component body can be prevented by covering the metal layer 5 with the conductive resin layer 6 to thereby reduce the stress generated in the metal layer 5 (see Japanese Unexamined Patent Application Publication No. 2001-76957).
It is also described that the development of cracks in the ceramic component body 2 due to thermal strain of the metal layer 5 or the development of cracks in the ceramic electronic component attached to the wiring board due to bending of the wiring board can be prevented when the ratio between the wrapping length of the metal layer 5 at the side surface of the ceramic component body 2 and the wrapping length of the conductive resin layer 6 is adjusted to a given ratio (see Japanese Unexamined Patent Application Publication No. 10-284343).
In such a ceramic electronic component, a stress caused by metal sintering shrinkage is concentrated on the end of the metal layer at the side surface of the ceramic electronic component body when a conductive paste is supplied and printed to the end surface of the ceramic electronic component body. Such a stress cannot be reduced even when the metal layer is covered with the conductive resin layer. When the wiring board to which the ceramic electronic component is attached bends to apply a stress caused by the bending of the wiring board, cracks are likely to develop at the end of the metal layer in the ceramic component body. Such cracks reach the internal electrodes, the properties of the ceramic electronic component are affected. For example, in the case of a laminated ceramic capacitor, the electric capacity decreases.